This week, Canon published a Service Notice to its websites urging photographers not to use lithium or lithium-ion batteries in its Speedlites, battery packs, and macro twin light products, surprising many that this was suddenly an issue. The thing is, it’s not sudden at all, and almost every manufacturer cautions against it. The long list of affected products includes 21 Canon Speedlites — which is the company’s term for shoe-mount flash units, which are also colloquially called speedlights — as well as four macro twin light strobes and four compact battery packs. The notice is classified as an “update,” which likely means this was a service notice that had previously been posted but had been updated with more products this month. “Please note that lithium batteries and lithium-ion batteries cannot be used with the Speedlites/Macro Ring Lites/Macro Twin Lights, and compact battery packs in general.…